Variable displacement swash plate type compressor

ABSTRACT

A variable displacement swash plate type compressor includes an actuator having a movable body and a control pressure chamber. An acting portion capable of pressing a swash plate by the pressure in the control pressure chamber is formed at the movable body, and an acted portion that abuts on and is pressed by the acting portion is formed at the swash plate. The acting portion abuts on the acted portion at an operative position, which moves in accordance with the change of an inclination angle of the swash plate. A top-dead-center corresponding portion is defined in the swash plate, and the operative position when the inclination angle is maximum is closer to the top-dead-center corresponding portion as compared to the operative position when the inclination angle is minimum.

TECHNICAL FIELD

The present invention relates to a variable displacement swash platetype compressor.

BACKGROUND ART

Patent Literature 1 discloses a conventional variable displacement swashplate type compressor (hereinafter referred to as a compressor). Thiscompressor comprises a housing, a drive shaft, a swash plate, a linkmechanism, a plurality of pistons, a conversion mechanism, and acapacity control mechanism.

In the housing, a suction chamber, a discharge chamber, a swash platechamber and a plurality of cylinder bores are formed. The drive shaft isrotatably supported by the housing. The swash plate is rotatable in theswash plate chamber by rotation of the drive shaft. The link mechanismis provided between the drive shaft and the swash plate and permitschange of an inclination angle of the swash plate with respect to adirection perpendicular to a driving axis of the drive shaft. The linkmechanism has a lug member and a transmission member. The lug member isfixed to the drive shaft in the swash plate chamber. The transmissionmember is provided integrally with the swash plate in the swash platechamber, and transmits rotation of the lug member to the swash plate.The pistons are reciprocally accommodated in respective cylinder bores.The conversion mechanism reciprocates the pistons in the cylinder boresat a stroke corresponding to the inclination angle by rotation of theswash plate. The capacity control mechanism has a supply passage, ableed passage and a control valve. The supply passage providescommunication between the discharge chamber and the swash plate chamber.The bleed passage provides communication between the swash plate chamberand the suction chamber. The control valve is capable of changing thepressure in the swash plate chamber by regulating an opening degree ofthe supply passage.

In the compressor, when the control valve increases the pressure in theswash plate chamber, the inclination angle becomes small and the strokeof the pistons decreases. Therefore, a compression capacity per rotationof the drive shaft becomes small. On the other hand, when the controlvalve decreases the pressure in the swash plate chamber, the inclinationangle of the swash plate becomes large, and the stroke of the pistonsincreases. Therefore, the compression capacity per rotation of the driveshaft becomes large. In this manner, in this compressor, the dischargecapacity of refrigerant is changeable in response to the drivingconditions of a vehicle or the like on which the compressor is mounted.

However, in the case of changing the inclination angle by changing thepressure in the swash plate chamber like this compressor, it isnecessary to provide a sufficient amount of refrigerant in the swashplate chamber in order to change the inclination angle. Therefore, thesize of the compressor tends to be increased due to a large swash platechamber.

Furthermore, in this compressor, it is inevitable that blow-by gashaving a high pressure flows into the swash plate chamber. Furthermore,in this compressor, when the outside air temperature drops, therefrigerant in the swash plate chamber is likely to condense and liquidaccumulation occurs in the swash plate chamber. For these reasons, inthis compressor, it is difficult to change the inclination anglesuitably.

Therefore, a compressor as disclosed in Patent Literature 2 has alsobeen proposed. This compressor includes an actuator that is capable ofchanging an inclination angle, and a control mechanism that controls theactuator.

Specifically, the actuator has a lug member, a movable body that engageswith a swash plate so as to be rotatable integrally therewith and ismovable in the direction of a driving axis to change the inclinationangle, and a control pressure chamber that is defined by the lug memberand the movable body and moves the movable body by its internalpressure. The control mechanism has a control passage and a controlvalve. The control passage has a variable pressure passage thatcommunicates with the control pressure chamber, a low pressure passagethat communicates with a suction chamber and a swash plate chamber, anda high pressure passage that communicates with a discharge chamber. Apart of the variable pressure passage is formed in a drive shaft. Thecontrol valve regulates an opening degree of the variable pressurepassage, the low pressure passage and the high pressure passage. Inother words, the control valve allows the variable pressure passage tocommunicate with the low pressure passage or the high pressure passage.

In this compressor, when the control valve allows the variable pressurepassage to communicate with the high pressure passage, the pressure inthe control pressure chamber becomes higher than that of the swash platechamber. Thereby, the movable body of the actuator moves away from thelug member, and the inclination angle decreases. Therefore, the strokeof the pistons decreases and the discharge capacity becomes small. Onthe other hand, when the control valve allows the variable pressurepassage to communicate with the low pressure passage, the pressure inthe control pressure chamber becomes as low as that of the swash platechamber. Thereby, the movable body of the actuator approaches the lugmember, and the inclination angle increases. Therefore, the stroke ofthe pistons increases and the discharge capacity becomes large.

Since this compressor is configured to change the pressure in thecontrol pressure chamber, which has a smaller volume than the swashplate chamber, the amount of the refrigerant required to change theinclination angle can be reduced as compared to the compressorconfigured to change the pressure in the swash plate chamber, andthereby downsizing can be realized.

Furthermore, since this compressor is configured to change theinclination angle by changing the pressure in the control pressurechamber, the blow-by gas flowing into the swash plate chamber and theliquid accumulation in the swash plate chamber are less likely to exertan adverse effect on the change of the inclination angle.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2002-213350

Patent Literature 2: Japanese Patent Laid-Open No. 52-131204

SUMMARY OF INVENTION Technical Problem

However, in the compressor described in Patent Literature 2 describedabove, when a plane determined by the driving axis and a top-dead-centercorresponding portion of the swash plate is defined as a first imaginaryplane, the movable body of the actuator engages with the swash plate ata second imaginary plane that is perpendicular to the first imaginaryplane and includes the driving axis. In addition, an operative positionwhere the movable body abuts on the hinge ball moves in parallel withthe direction of the driving axis as the inclination angle of the swashplate changes. The same applies to an operative position where the hingeball abuts on the swash plate. That is, in this compressor, the distancebetween the operative position and the driving axis does not change evenwhen the inclination angle of the swash plate changes.

Therefore, in this compressor, at the time of decreasing the inclinationangle, it is necessary to increase a differential pressure between theswash plate chamber and the control pressure chamber (hereinafterreferred to as a variable differential pressure) to thereby move themovable body by a larger thrust force. That is, in this compressor, theload exerted on the movable body increases as the inclination angledecreases. Therefore, in this compressor, the amount of change in thevariable differential pressure when the inclination angle changes islarge; therefore, it is difficult to quickly change the inclinationangle in response to the driving conditions of a vehicle or the like,and controllability is lowered.

Furthermore, in this compressor, since the distance between theoperative position and the driving axis does not change, a stroke of themovable body in order to change the inclination angle of the swash plateis long in the direction of the driving axis. Consequently, it isinevitable to enlarge the compressor in the axial length, and therefore,there is a concern about mountability on a vehicle or the like.

The present invention has been made in the light of the conventionalcircumstances described above, and an object of the invention is toprovide a variable displacement swash plate type compressor capable ofexhibiting high controllability and excellent mountability.

Solution to Problem

A variable displacement swash plate type compressor of the presentinvention comprises: a housing in which a swash plate chamber and acylinder bore are formed; a drive shaft that is rotatably supported bythe housing; a swash plate that is rotatable in the swash plate chamberby rotation of the drive shaft; a link mechanism that is providedbetween the drive shaft and the swash plate and permits change of aninclination angle of the swash plate with respect to a directionperpendicular to a driving axis of the drive shaft; a piston that isreciprocally accommodated in the cylinder bore; a conversion mechanismthat reciprocates the piston in the cylinder bore at a strokecorresponding to the inclination angle by rotation of the swash plate;an actuator capable of changing the inclination angle; and a controlmechanism that controls the actuator,

wherein the link mechanism has a lug member that is fixed to the driveshaft in the swash plate chamber and a transmission member thattransmits rotation of the lug member to the swash plate,

the actuator has the lug member, a movable body that is rotatableintegrally with the swash plate and is capable of changing theinclination angle by moving in the direction of the driving axis, and acontrol pressure chamber that is defined by the lug member and themovable body and moves the movable body by changing its internalpressure by the control mechanism,

an acting portion that is capable of pressing the swash plate by thepressure in the control pressure chamber is formed at the movable body,

an acted portion that abuts on and is pressed by the acting portion isformed at the swash plate,

the acting portion abuts on the acted portion at an operative position,

the operative position moves in accordance with the change of theinclination angle,

a top-dead-center corresponding portion for positioning the piston atits top dead center is defined in the swash plate, and

the operative position when the inclination angle is maximum is closerto the top-dead-center corresponding portion as compared to theoperative position when the inclination angle is minimum.

In the compressor of the present invention, the transmission member ofthe link mechanism transmits rotation of the lug member to the swashplate. In addition, the operative position at which the acting portionof the movable body abuts on the acted portion of the swash plate movesin accordance with the change of the inclination angle of the swashplate. Specifically, the operative position when the inclination angleis maximum is closer to the top-dead-center corresponding portion of theswash plate as compared to the operative position when the inclinationangle is minimum.

Therefore, in this compressor, as compared with the case where theoperative position has a constant distance from the driving axis evenwhen the inclination angle of the swash plate changes, it is possible tomove the movable body without increasing the variable differentialpressure at the time of decreasing the inclination angle so as toprovide a large thrust force. That is, in this compressor, it ispossible to reduce the load exerted on the movable body at the time ofdecreasing the inclination angle. Consequently, in this compressor, theamount of change in the variable differential pressure when theinclination angle changes is small; therefore, it is easy to quicklychange the inclination angle in response to the driving conditions of avehicle or the like, and high controllability can be exhibited.

Furthermore, in this compressor, since the operative position moves asdescribed above in accordance with the change of the inclination angleof the swash plate, the stroke of the movable body in the direction ofthe driving axis can be reduced as compared with the case where theoperative position has a constant distance from the driving axis,provided that the range of their inclination angle is the same. Thissuppresses enlargement of the compressor in the axial length.

Accordingly, the compressor of the present invention is capable ofexhibiting high controllability and excellent mountability.

It is not impossible to employ such a configuration that, for example,the acting portion is connected to the acted portion with a connectionpin etc. However, in this case, there is a risk that the configurationof a connection portion changes the posture of the movable body. Inaddition, because the number of components increases, the configurationof the compressor is complicated and manufacturing cost increases. Incontrast, in the compressor of the present invention, the movable bodymerely abuts directly on and presses the swash plate to change theinclination angle of the swash plate, and therefore, the posture of themovable body is less likely to change. In addition, in this compressor,it is possible to suppress complication of the configuration, andreduction in manufacturing cost can be realized.

The control mechanism may have a control passage and a control valve.The control passage may have a variable pressure passage thatcommunicates with the control pressure chamber, a low pressure passagethat communicates with a suction chamber or a swash plate chamber, and ahigh pressure passage that communicates with a discharge chamber.

It is preferable that the drive shaft is inserted through the movablebody, and the movable body is capable of being fitted to the lug member.In this case, a space for allowing the movable body to move in thedirection of the driving axis can be suitably provided between the lugmember and the swash plate.

Furthermore, the movable body may have a movable cylindrical portionthat is formed into a cylindrical shape and coaxial with the drivingaxis. It is preferable that the lug member has a fixed cylindricalportion that is formed into a cylindrical shape and is coaxial with thedriving axis at an outer circumferential side of the movable cylindricalportion to thereby provide the control pressure chamber in the movablecylindrical portion. In this case, by fitting the movable cylindricalportion into the fixed cylindrical portion, the movable body can befitted to the lug member. Furthermore, since the control pressurechamber is provided in the movable cylindrical portion by the fixedcylindrical portion, the control pressure chamber can be suitably formedbetween the lug member and the movable body.

Furthermore, in this case, a first seal member that seals the controlpressure chamber may be provided between the movable cylindrical portionand the drive shaft. In addition, it is preferable that a second sealmember that seals the control pressure chamber is provided between themovable cylindrical portion and the fixed cylindrical portion. Thereby,hermeticity of the control pressure chamber can be suitably ensured.Here, as the first seal member and the second seal member, various sealscan be employed besides O-rings etc. The first seal member and thesecond seal member may be of the same kind or different kinds.

A thrust bearing that receives a thrust force which acts on the pistonmay be provided between the housing and the lug member. In addition, itis preferable that the movable cylindrical portion is smaller indiameter than the thrust bearing and capable of advancing to an innerside of the thrust bearing.

In this case, it is possible for the thrust bearing to suitably receivea suction reaction force which acts on the piston during a suction phaseand a compression reaction force which acts on the piston during acompression phase. Furthermore, by allowing the movable cylindricalportion to advance to the inner side of the thrust bearing, even if theaxial length of the compressor is short, the space for allowing themovable body to move in the direction of the driving axis can besufficiently ensured.

In the compressor of the present invention, the acting portion and theacted portion come into point-contact or line-contact with each other atthe operative position. In this case, the contact area between theacting portion and the acted portion can be made small. Here, thestraight line on which the operative position and the acted portion arebrought into line-contact is perpendicular to the first imaginary planedetermined by the top-dead-center corresponding portion of the swashplate and the driving axis. Furthermore, when bringing the actingportion into point-contact or line-contact with the acted portion at theoperative position, it is preferable that either one of a portion in theacting portion where it abuts on the acted portion and a portion in theacted portion where it abuts on the acting portion is formed into acurved shape.

Furthermore, the position in the movable body where the acting portionis formed and the position in the swash plate where the acted portion isformed can be designed as appropriate. In particular, in the compressorof the present invention, the acting portion and the acted portion maybe located eccentrically toward the top-dead-center correspondingportion from the driving axis. It is preferable that the operativeposition moves toward the driving axis when the inclination angledecreases.

In this case, a space for allowing the movable body to move in thedirection of the driving axis is easily provided between the lug memberand the swash plate without disrupting the change of the inclinationangle. Therefore, in this compressor, it is possible to increase thediameter of the actuator so as to quickly move the movable body by asufficient thrust force while suppressing enlargement of the compressorin the axial length.

The acting portion may have an acting surface that extends in thedirection perpendicular to the driving axis. It is preferable that theacted portion has a protrusion that protrudes from the swash plate andabuts on the acting surface. In this case, the acting portion and theacted portion can be suitably brought into point-contact or line-contactwith each other.

It is preferable that the acting portion protrudes from the movablecylindrical portion toward the top-dead-center corresponding portion. Inthis case, the acting portion easily abuts on the acted portion.

It is preferable that the swash plate has a swash plate main body thatis formed with an insertion hole, through which the drive shaft isinserted, and the acted portion that is integrally formed with the swashplate main body. In this case, it is possible to reduce the number ofcomponents in the compressor, facilitate manufacturing, and reducemanufacturing cost.

It is also preferable that the swash plate has a swash plate main bodythat is formed with an insertion hole, through which the drive shaft isinserted, and the acted portion that is fixed to the swash plate mainbody. In this case, it is possible to improve the flexibility of designwith respect to the swash plate main body and the acted portion.

In the compressor of the present invention, a suction chamber and adischarge chamber may be formed in the housing. It is preferable thatthe suction chamber and the swash plate chamber communicate with eachother. In this case, the pressure in the swash plate chamber can be madelow as well as the suction chamber.

Furthermore, the control mechanism may have a control passage thatprovides communication between the control pressure chamber and thesuction chamber and/or the discharge chamber, and a control valve thatis capable of regulating an opening degree of the control passage. It ispreferable that at least a part of the control passage is formed in thedrive shaft. In this case, it is possible to suitably change thepressure in the control pressure chamber and suitably move the movablebody while downsizing the control mechanism.

A pressure regulation chamber that communicates with the controlpressure chamber through the control passage and allows a pressuretherein to be changed by the control valve may be formed between thehousing and one end of the drive shaft. It is preferable that a thirdseal member that seals the pressure regulation chamber is providedbetween the housing and the drive shaft.

In this case, when the pressure in the pressure regulation chamber ischanged by the control valve, the control pressure chamber moves themovable body. By the third seal member, hermeticity of the pressureregulation chamber can be suitably ensured. Here, as the third sealmember, various seals can be employed besides O-rings etc. as in thecase of the first and second seal members described above. Furthermore,the third seal member may be of the same kind as or a different kindfrom the first and second seal members.

Advantageous Effects of Invention

The compressor of the present invention is capable of exhibiting highcontrollability and excellent mountability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a compressor according to Embodiment 1 atthe time of maximum displacement.

FIG. 2 is a schematic diagram showing a control mechanism of thecompressor according to Embodiment 1.

FIG. 3 is an enlarged sectional view of an essential part of thecompressor according to Embodiment 1, showing a rear end portion of adrive shaft.

FIG. 4 is an enlarged sectional view of an essential part of thecompressor according to Embodiment 1, showing an actuator.

FIG. 5 is a front perspective view showing a swash plate of thecompressor according to Embodiment 1.

FIG. 6 is a sectional view of the compressor according to Embodiment 1at the time of minimum displacement.

FIG. 7A is an enlarged sectional view of an essential part of thecompressor according to Embodiment 1, showing an operative positionwhere an acting portion abuts on an acted portion when an inclinationangle of the swash plate is maximum.

FIG. 7B is an enlarged sectional view of an essential part of thecompressor according to Embodiment 1, showing the operative positionwhen the inclination angle is minimum.

FIG. 8 is a graph showing a relation between the inclination angle and avariable differential pressure.

FIG. 9 is a schematic view of the compressor according to Embodiment 1and a compressor of a comparative example, showing a difference instrokes of movable bodies.

FIG. 10 is a sectional view of a compressor according to Embodiment 2 atthe time of maximum displacement.

DESCRIPTION OF EMBODIMENTS

Hereinafter, Embodiments 1 and 2, which embody the present invention,will be described with reference to the drawings. The compressors ofEmbodiments 1 and 2 are variable displacement single-head swash platetype compressors. These compressors are both mounted on vehicles andconstitute refrigeration circuits of vehicle air-conditioning apparatus.

Embodiment 1

As shown in FIG. 1, the compressor of Embodiment 1 includes a housing 1,a drive shaft 3, a swash plate 5, a link mechanism 7, a plurality ofpistons 9, a plurality of pairs of shoes 11 a and 11 b, an actuator 13,and a control mechanism 15 which is shown in FIG. 2. In FIG. 1, theillustration of the swash plate 5 is partially simplified for ease ofexplanation. The same applies to FIGS. 6 and 10, which will be describedlater.

As shown in FIG. 1, the housing 1 has a front housing 17 that is locatedat a front side in the compressor, a rear housing 19 that is located ata rear side in the compressor, a cylinder block 21 that is locatedbetween the front housing 17 and the rear housing 19, and a valve unit23.

The front housing 17 has a front wall 17 a that extends in the up-downdirection of the compressor at the front side, and a circumferentialwall 17 b that is integrated with the front wall 17 a and extendsrearward from the front side of the compressor. By the front wall 17 aand the circumferential wall 17 b, the front housing 17 is formed into asubstantially cylindrical shape with a bottom. Furthermore, by the frontwall 17 a and the circumferential wall 17 b, a swash plate chamber 25 isformed in the front housing 17.

A boss 17 c that protrudes frontward is formed on the front wall 17 a. Ashaft seal device 27 is provided in the boss 17 c. Furthermore, a firstshaft hole 17 d that extends in the front-rear direction of thecompressor is formed in the boss 17 c. A first sliding bearing 29 a isprovided in the first shaft hole 17 d.

An inlet port 250 that communicates with the swash plate chamber 25 isformed through the circumferential wall 17 b. Through the inlet port250, the swash plate chamber 25 is connected to an evaporator, which isnot illustrated.

A part of the control mechanism 15 is provided in the rear housing 19.In addition, a first pressure regulation chamber 31 a, a suction chamber33 and a discharge chamber 35 are formed in the rear housing 19. Thefirst pressure regulation chamber 31 a is disposed at the center of therear housing 19. The discharge chamber 35 is disposed annularly at anouter circumferential side in the rear housing 19. Furthermore, thesuction chamber 33 is formed annularly between the first pressureregulation chamber 31 a and the discharge chamber 35 in the rear housing19. The discharge chamber 35 is connected to an outlet port which is notillustrated.

Cylinder bores 21 a, the number of which is the same as that of thepistons 9, are formed in the cylinder block 21 at equiangular intervalsin a circumferential direction. Front end sides of the respectivecylinder bores 21 a communicate with the swash plate chamber 25.Furthermore, a retainer groove 21 b that restricts a lift amount ofsuction reed valves 41 a, which will be described later, is formed inthe cylinder block 21.

Furthermore, a second shaft hole 21 c that extends in the front-reardirection of the compressor and communicates with the swash platechamber 25 is formed through the cylinder block 21. A second slidingbearing 29 b is provided in the second shaft hole 21 c. Furthermore, aspring chamber 21 d is formed in the cylinder block 21. The springchamber 21 d is located between the swash plate chamber 25 and thesecond shaft hole 21 c. A return spring 37 is disposed in the springchamber 21 d. The return spring 37 urges the swash plate 5 frontward inthe swash plate chamber 25 when the inclination angle becomes minimum.Furthermore, a suction passage 39 that communicates with the swash platechamber 25 is formed in the cylinder block 21.

The valve unit 23 is provided between the rear housing 19 and thecylinder block 21. The valve unit 23 includes a valve plate 40, asuction valve plate 41, a discharge valve plate 43 and a retainer plate45.

Suction ports 40 a, the number of which is the same as that of thecylinder bores 21 a, are formed in the valve plate 40, the dischargevalve plate 43 and the retainer plate 45. Furthermore, discharge ports40 b, the number of which is the same as that of the cylinder bores 21a, are formed in the valve plate 40 and the suction valve plate 41. Therespective cylinder bores 21 a communicate with the suction chamber 33through the respective suction ports 40 a, and communicate with thedischarge chamber 35 through the respective discharge ports 40 b.Furthermore, a first communication hole 40 c and a second communicationhole 40 d are formed in the valve plate 40, the suction valve plate 41,the discharge valve plate 43 and the retainer plate 45. Through thefirst communication hole 40 c, the suction chamber 33 and the suctionpassage 39 communicate with each other.

The suction valve plate 41 is provided on the front surface of the valveplate 40. A plurality of suction reed valves 41 a that are capable ofopening and closing the respective suction ports 40 a by elasticdeformation are formed in the suction valve plate 41. Furthermore, thedischarge valve plate 43 is provided on the rear surface of the valveplate 40. A plurality of discharge reed valves 43 a that are capable ofopening and closing the respective discharge ports 40 b by elasticdeformation are formed in the discharge valve plate 43. The retainerplate 45 is provided on the rear surface of the discharge valve plate43. The retainer plate 45 restricts a lift amount of the discharge reedvalves 43 a.

The drive shaft 3 is inserted from a boss 17 c to the rear side of thehousing 1. The front end side of the drive shaft 3 is supported by theshaft seal device 27 in the boss 17 c and supported by the first slidingbearing 29 a in the first shaft hole 17 d. The rear end side of thedrive shaft 3 is supported by the second sliding bearing 29 b in thesecond shaft hole 21 c. In this manner, the drive shaft 3 is rotatablysupported around a driving axis O with respect to the housing 1. Asecond pressure regulation chamber 31 b is defined by the rear end ofthe drive shaft 3 in the second shaft hole 21 c. The second pressureregulation chamber 31 b communicates with the first pressure regulationchamber 31 a through the second communication hole 40 d. A pressureregulation chamber 31 is formed by the first and the second pressureregulation chambers 31 a and 31 b.

As shown in FIG. 3, ring grooves 3 c and 3 d are formed at the rear endof the drive shaft 3. O-rings 49 a and 49 b are provided in the ringgrooves 3 c and 3 d, respectively. The pressure regulation chamber 31 issealed with the O-rings 49 a and 49 b, whereby the swash plate chamber25 does not communicate with the pressure regulation chamber 31. TheO-rings 49 a and 49 b correspond to the third seal member in the presentinvention.

As shown in FIG. 1, the link mechanism 7, the swash plate 5 and theactuator 13 are attached to the drive shaft 3. The link mechanism 7includes a lug plate 51, a pair of lug arms 53 that are formed at thelug plate 51, and a pair of swash plate arms 5 e and 5 f. The lug plate51 corresponds to the lug member in the present invention. Furthermore,the swash plate arms 5 e and 5 f correspond to the transmission memberin the present invention.

The lug plate 51 is formed into a substantially annular shape. The lugplate 51 is press-fitted to the drive shaft 3 and rotatable integrallywith the drive shaft 3. The lug plate 51 is located at the front endside in the swash plate chamber 25 and disposed in front of the swashplate 5. Furthermore, a thrust bearing 55 is provided between the lugplate 51 and the front wall 17 a.

As shown in FIG. 4, a fixed cylindrical portion 51 a that is formed intoa cylindrical shape and extends in the front-rear direction of the lugplate 51 is provided in a recessed manner in the lug plate 51. As shownin FIG. 1, the fixed cylindrical portion 51 a extends from the rear endsurface of the lug plate 51 to a position on an inner side of the thrustbearing 55 in the lug plate 51.

The lug arms 53 extend rearward from the lug plate 51. Furthermore, acam surface 51 b is formed at the lug plate 51 at a position between thelug arms 53. In FIG. 1 etc., only one of the lug arms 53 is illustratedfor ease of explanation.

As shown in FIG. 5, the swash plate 5 has a swash plate main body 50,the swash plate arms 5 e and 5 f, and a protrusion 5 g. The protrusion 5g corresponds to the acted portion in the present invention.

The swash plate main body 50 is formed into an annular flat-plate shapeand has a front surface 5 a and a rear surface 5 b; in addition, atop-dead-center corresponding portion T for positioning the respectivepistons 9 at their top dead center is defined therein. A restrictionportion 5 c that protrudes frontward from the swash plate 5 is formed onthe front surface 5 a. As shown in FIG. 1, the restriction portion 5 cabuts on the lug plate 51 when the inclination angle of the swash plate5 becomes maximum. Furthermore, the swash plate main body 50 is formedwith an insertion hole 5 d. The drive shaft 3 is inserted through theinsertion hole 5 d.

As shown in FIG. 5, the swash plate arms 5 e and 5 f are formed on thefront surface 5 a of the swash plate main body 50 at positions eccentrictoward the top-dead-center corresponding portion T of the swash plate 5from the driving axis O. The swash plate arms 5 e and 5 f extendfrontward from the front surface 5 a.

The protrusion 5 g protrudes frontward from the front surface 5 a and isintegrated with the swash plate main body 50. The protrusion 5 g isformed into a substantially hemispherical shape, and locatedeccentrically toward the top-dead-center corresponding portion T of theswash plate 5 from the driving axis O so as to be disposed between theswash plate arm 5 e and the swash plate arm 5 f.

As shown in FIG. 1, by inserting the swash plate arms 5 e and 5 fbetween the lug arms 53, the lug plate 51 is connected to the swashplate 5. Thereby, the swash plate 5 is rotatable along with the lugplate 51 in the swash plate chamber 25. The tip ends of the swash platearms 5 e and 5 f abut on the cam surface 51 b.

By connecting the lug plate 51 to the swash plate 5, the swash platearms 5 e and 5 f and the protrusion 5 g are located eccentrically towardthe top-dead-center corresponding portion T of the swash plate 5 fromthe driving axis O. In addition, the swash plate arms 5 e and 5 f slideon the cam surface 51 b, whereby the swash plate 5 is able to change itsinclination angle with respect to the direction perpendicular to thedriving axis O from the maximum inclination angle shown in FIG. 1 to theminimum inclination angle shown in FIG. 6 while substantiallymaintaining the position of the top-dead-center corresponding portion T.

As shown in FIG. 4, the actuator 13 includes the lug plate 51, a movablebody 13 a and a control pressure chamber 13 b.

The movable body 13 a, through which the drive shaft 3 is inserted, isslidable in contact with the drive shaft 3 to move in the direction ofthe driving axis O. The movable body 13 a is formed into a cylindricalshape and coaxial with the drive shaft 3, and the diameter thereof issmaller than that of the thrust bearing 55 shown in FIG. 1. As shown inFIG. 4, the movable body 13 a has a first movable cylindrical portion131, a second movable cylindrical portion 132 and a third movablecylindrical portion 133. The first movable cylindrical portion 131 islocated at a rear end side in the movable body 13 a and has the smallestdiameter in the movable body 13 a. The second movable cylindricalportion 132 continues from the front end of the first movablecylindrical portion 131 and is formed such that its diameter increasesgradually toward the front side of the movable body 13 a. The thirdmovable cylindrical portion 133 continues from the front end of thesecond movable cylindrical portion 132 and extends toward the front sideof the movable body 13 a. The third movable cylindrical portion 133 hasthe largest diameter in the movable body 13 a.

Furthermore, an acting portion 134 is integrally formed at the rear endof the first movable cylindrical portion 131. As shown in FIG. 1, theacting portion 134 extends vertically from a position near the drivingaxis O toward the top-dead-center corresponding portion T of the swashplate 5, and is located eccentrically toward the top-dead-centercorresponding portion T of the swash plate 5 from the driving axis O.The acting portion 134 has an acting surface 134 a which is formed intoa flat shape. As shown in FIG. 7, the acting surface 134 a comes intopoint-contact with the protrusion 5 g at an operative position F.Thereby, the movable body 13 a is rotatable integrally with the lugplate 51 and the swash plate 5. Here, since the protrusion 5 g and theacting portion 134 are located eccentrically toward the top-dead-centercorresponding portion T of the swash plate 5 from the driving axis O,the operative position F is also located eccentrically toward thetop-dead-center corresponding portion T of the swash plate 5 from thedriving axis O as shown in FIG. 1.

The movable body 13 a is capable of being fitted to the lug plate 51 byallowing the second movable cylindrical portion 132 and the thirdmovable cylindrical portion 133 shown in FIG. 4 to advance into thefixed cylindrical portion 51 a (see FIG. 1). When the second movablecylindrical portion 132 and the third movable cylindrical portion 133has advanced farthest into the fixed cylindrical portion 51 a, the thirdmovable cylindrical portion 133 reaches a position on an inner side ofthe thrust bearing 55 in the fixed cylindrical portion 51 a.

As shown in FIG. 4, the control pressure chamber 13 b is formed by thesecond movable cylindrical portion 132, the third movable cylindricalportion 133, the fixed cylindrical portion 51 a and the drive shaft 3.Furthermore, a ring groove 131 a is formed in the inner circumferentialsurface of the first movable cylindrical portion 131, and a ring groove133 a is formed in the outer circumferential surface of the thirdmovable cylindrical portion 133. O-rings 49 c and 49 d are provided inthe ring grooves 131 a and 133 a, respectively. The O-ring 49 ccorresponds to the first seal member in the present invention, and theO-ring 49 d corresponds to the second seal member in the presentinvention. The control pressure chamber 13 b is sealed with the O-rings49 c and 49 d, whereby the hermeticity of the control pressure chamber13 b is ensured.

As shown in FIG. 1, an axial path 3 a that extends in the direction ofthe driving axis O from the rear end of the drive shaft 3 toward thefront end thereof and a radial path 3 b that extends radially from thefront end of the axial path 3 a and opens at the outer circumferentialsurface of the drive shaft 3 are formed in the drive shaft 3. The rearend of the axial path 3 a opens to the pressure regulation chamber 31.The radial path 3 b opens to the control pressure chamber 13 b. Throughthe axial path 3 a and the radial path 3 b, the pressure regulationchamber 31 and the control pressure chamber 13 b communicate with eachother.

The drive shaft 3 is connected to a pulley or an electromagnetic clutch,which are not illustrated, via a screw portion 3 e which is formed atthe tip end thereof.

The pistons 9 are respectively accommodated in the respective cylinderbores 21 a and capable of reciprocating in the respective cylinder bores21 a. Compression chambers 57 are defined in the respective cylinderbores 21 a by the respective pistons 9 and the valve unit 23.

Furthermore, an engaging portion 9 a is formed in a recessed manner ineach of the pistons 9. The shoes 11 a and 11 b formed into ahemispherical shape are provided in the respective engaging portions 9a. The shoes 11 a and 11 b convert the rotation of the swash plate 5into reciprocal movement of the pistons 9. The shoes 11 a and 11 bcorrespond to the conversion mechanism in the present invention. In thismanner, the pistons 9 are able to reciprocate in the cylinder bores 21 aat a stroke corresponding to the inclination angle of the swash plate 5.Alternatively, instead of the shoes 11 a and 11 b, it is also possibleto employ a wobble type conversion mechanism, in which a wobble plate issupported at the side of the rear surface 5 b of the swash plate mainbody 50 via a thrust bearing and the wobble plate is connected to therespective pistons 9 via connecting rods.

As shown in FIG. 2, the control mechanism 15 has a low pressure passage15 a, a high pressure passage 15 b, a control valve 15 c, an orifice 15d, the axial path 3 a and the radial path 3 b. A control passage in thepresent invention is formed by the low pressure passage 15 a, the highpressure passage 15 b, the axial path 3 a and the radial path 3 b.Furthermore, the axial path 3 a and the radial path 3 b serve asvariable pressure passages.

The low pressure passage 15 a is connected to the pressure regulationchamber 31 and the suction chamber 33. Thereby, the control pressurechamber 13 b, the pressure regulation chamber 31 and the suction chamber33 communicate with one another through the low pressure passage 15 a,the axial path 3 a and the radial path 3 b. The high pressure passage 15b is connected to the pressure regulation chamber 31 and the dischargechamber 35. The control pressure chamber 13 b, the pressure regulationchamber 31 and the discharge chamber 35 communicate with one anotherthrough the high pressure passage 15 b, the axial path 3 a and theradial path 3 b. Furthermore, the high pressure passage 15 b is providedwith the orifice 15 d, whereby the flow rate of the refrigerant flowingthrough the high pressure passage 15 b is reduced.

The control valve 15 c is provided at the low pressure passage 15 a. Thecontrol valve 15 c is capable of regulating the flow rate of therefrigerant flowing through the low pressure passage 15 a based on thepressure in the suction chamber 33.

In this compressor, a pipe that leads to the evaporator is connected tothe inlet port 250 shown in FIG. 1, and a pipe that leads to a condenseris connected to the outlet port. The condenser is connected to theevaporator via pipes and an expansion valve. The refrigeration circuitof vehicle air-conditioning apparatus is constituted by the compressor,the evaporator, the expansion valve, the condenser and the like.Illustration of the evaporator, the expansion valve, the condenser andthe pipes is omitted.

In the compressor configured as above, by rotation of the drive shaft 3,the swash plate 5 rotates and the pistons 9 reciprocate in therespective cylinder bores 21 a. The volume of the compression chambers57 thus changes in response to the stroke of the pistons 9. Therefrigerant introduced from the evaporator into the swash plate chamber25 through the inlet port 250 thus passes the suction chamber 33 throughthe suction passage 39 and then is compressed in the compressionchambers 57. Subsequently, the refrigerant compressed in the compressionchambers 57 is discharged to the discharge chamber 35 and thendischarged to the condenser from the outlet port.

During this time, in this compressor, a piston compression force thatreduces the inclination angle of the swash plate 5 acts on the swashplate 5, the lug plate 51 and the like. By changing the inclinationangle of the swash plate 5 to increase or decrease the stroke of thepistons 9, it is possible to perform capacity control in thiscompressor.

Specifically, in the control mechanism 15, when the control valve 15 cshown in FIG. 2 increases the flow rate of the refrigerant flowingthrough the low pressure passage 15 a, the refrigerant in the dischargechamber 35 is less likely to pass the high pressure passage 15 b and theorifice 15 d and be stored in the pressure regulation chamber 31.Therefore, the pressure in the control pressure chamber 13 b becomessubstantially equal to that in the suction chamber 33. As a result, asshown in FIG. 1, due to the piston compression force acting on the swashplate 5, in the actuator 13, the volume of the control pressure chamber13 b decreases and the movable body 13 a moves from the side of theswash plate 5 toward the lug plate 51 in the direction of the drivingaxis O. Then, in the movable body 13 a, the second movable cylindricalportion 132 and the third movable cylindrical portion 133 advance intothe fixed cylindrical portion 51 a.

At the same time, in this compressor, due to the piston compressionforce and the urging force of the return spring 37 acting on the swashplate 5, the swash plate arms 5 e and 5 f slide on the cam surface 51 bso as to move away from the driving axis O. Therefore, a bottom deadcenter side of the swash plate 5 pivots in a clockwise direction whilesubstantially maintaining the position of the top-dead-centercorresponding portion T. In this manner, in this compressor, theinclination angle of the swash plate 5 with respect to the directionperpendicular to the driving axis O of the drive shaft 3 increases.Thereby, in this compressor, the stroke of the pistons 9 increases andthe discharge capacity per rotation of the drive shaft 3 becomes large.Here, the inclination angle of the swash plate 5 shown in FIG. 1 is themaximum inclination angle in this compressor. When the swash plate 5 isat the maximum inclination angle, the swash plate arms 5 e and 5 f abuton the cam surface 51 b at a first position P1.

On the other hand, when the control valve 15 c shown in FIG. 2 decreasesthe flow rate of the refrigerant flowing through the low pressurepassage 15 a, the refrigerant in the discharge chamber 35 is more likelyto pass the high pressure passage 15 b and the orifice 15 d and bestored in the pressure regulation chamber 31. Therefore, the pressure inthe control pressure chamber 13 b becomes substantially equal to that ofthe discharge chamber 35, and the pressure in the control pressurechamber 13 b becomes higher than that of the swash plate chamber 25. Asa result, as shown in FIG. 6, in the actuator 13, the volume of thecontrol pressure chamber 13 b increases and the movable body 13 a movesaway from the lug plate 51 toward the swash plate 5 in the direction ofthe driving axis O.

Thereby, in this compressor, the acting surface 134 a of the actingportion 134 operates in such a manner as to press the protrusion 5 grearward in the swash plate chamber 25 at the operative position F.Therefore, the swash plate arms 5 e and 5 f slide on the cam surface 51b so as to approach the driving axis O, and the bottom dead center sideof the swash plate 5 pivots in a counterclockwise direction whilesubstantially maintaining the position of the top-dead-centercorresponding portion T. In this manner, in this compressor, theinclination angle of the swash plate 5 with respect to the directionperpendicular to the driving axis O of the drive shaft 3 decreases.Thereby, in this compressor, the stroke of the pistons 9 decreases andthe discharge capacity per rotation of the drive shaft 3 becomes small.Furthermore, when the inclination angle decreases, the swash plate 5abuts on the return spring 37. Here, the inclination angle of the swashplate 5 shown in FIG. 6 is the minimum inclination angle in thiscompressor. When the swash plate 5 is at the minimum inclination angle,the swash plate arms 5 e and 5 f abut on the cam surface 51 b at asecond position P2.

As described above, this compressor employs the actuator 13 so as tochange the inclination angle of the swash plate 5 by changing thepressure in the control pressure chamber 13 b, which has a smallervolume than the swash plate chamber 25. Therefore, in this compressor,the amount of the refrigerant required to change the inclination anglecan be reduced as compared to the compressor configured to change theinclination angle by changing the pressure in the swash plate chamber25. As a result, this compressor is capable of suppressing enlargementof the swash plate chamber 25 and the housing 1.

Furthermore, in this compressor, the swash plate arms 5 e and 5 f of thelink mechanism 7 transmit the rotation of the lug plate 51 to the swashplate 5 and permit change of the inclination angle while substantiallymaintaining the position of the top-dead-center corresponding portion Tof the swash plate 5. Furthermore, the acting portion 134 of the movablebody 13 a and the protrusion 5 g of the swash plate 5 are locatedeccentrically toward the top-dead-center corresponding portion T of theswash plate 5 from the driving axis O. The acting surface 134 a of theacting portion 134 comes into point-contact with the protrusion 5 g atthe operative position F, and in order to decrease the inclination angleof the swash plate 5, the acting surface 134 a presses the protrusion 5g. The operative position F moves in accordance with the change of theinclination angle.

Specifically, in this compressor, as shown in FIG. 7A, when theinclination angle is maximum, the operative position F is located at aposition near the top-dead-center corresponding portion T of the swashplate 5. Then, as the inclination angle decreases, the position wherethe swash plate arms 5 e and 5 f abuts on the cam surface 51 b movestoward the second position P2. Thereby, in this compressor, as shown bythe white arrow in FIG. 7B, the operative position F moves toward thedriving axis O as the inclination angle of the swash plate 5 decreases.In other words, the operative position F when the inclination angle ismaximum is closer to the top-dead-center corresponding portion T of theswash plate 5 as compared to the operative position F when theinclination angle is minimum. Here, in this compressor, even when theinclination angle becomes minimum, the operative position F does notmove to the opposite side of the top-dead-center corresponding portion Tacross the driving axis O.

Therefore, in this compressor, as compared with the case where theoperative position F has a constant distance from the driving axis O, itis possible to move the movable body 13 a without increasing thevariable differential pressure at the time of decreasing the inclinationangle so as to provide a large thrust force. That is, in thiscompressor, the load exerted on the movable body 13 a at the time ofdecreasing the inclination angle can be reduced. Consequently, in thiscompressor, the amount of change in the variable differential pressurewhen the inclination angle changes is small; therefore, it is easy tochange the inclination angle quickly in response to the drivingconditions of the vehicle on which the compressor is mounted, and highcontrollability can be exhibited.

Furthermore, in this compressor, since the operative position F moves asdescribed above in accordance with the change of the inclination angleof the swash plate 5, the stroke of the movable body 13 a in thedirection of the driving axis O is reduced as compared to the compressorin which the operative position F has a constant distance from thedriving axis O, provided that the range of their inclination angle isthe same. Therefore, enlargement of the compressor in the axial lengthis suppressed. These operations will be specifically described below bycomparison with a comparative example.

The compressor of the comparative example is configured by partiallychanging the compressor of Embodiment 1 such that the protrusion 5 g andthe acting portion 134 are not provided in the swash plate 5 and themovable body 13 a. Thereby, in the compressor of the comparativeexample, the rear end of the first movable cylindrical portion 131 ofthe movable body 13 a abuts on the front surface 5 a at a positionaround the insertion hole 5 d. Therefore, in the compressor of thecomparative example, the movable body 13 a abuts on the swash plate 5 ata position almost on the driving axis O. As a result, in thiscompressor, when the inclination angle of the swash plate 5 changes, theoperative position between the movable body 13 a and the swash plate 5moves in parallel with the direction of the driving axis O. That is, inthe compressor of the comparative example, the distance between theoperative position and the driving axis O is constant and unchanged evenwhen the inclination angle changes.

Therefore, as the graph in FIG. 8 shows, in the compressor of thecomparative example, it is necessary to increase the variabledifferential pressure when the inclination angle decreases so as to movethe movable body 13 a by a larger thrust force. In contrast, in thecompressor of Embodiment 1, it is possible to move the movable body 13 awithout increasing the variable differential pressure to thereby providea large thrust force as described above. Consequently, in the compressorof Embodiment 1, the variable differential pressure required at the timeof changing the inclination angle can be made small and almost uniformas a whole.

Furthermore, as shown in FIG. 9, in the compressor of the comparativeexample, in order to displace the swash plate 5 at the maximuminclination angle in this drawing (see the double-dashed chain line)until it reaches the minimum inclination angle, the movable body 13 aneeds to move by a distance S2 in the direction of the driving axis O.

In contrast, in the compressor of Embodiment 1, it is sufficient if themovable body 13 a moves by a distance S1 in the direction of the drivingaxis O in order to displace the swash plate 5 at the maximum inclinationangle until it reaches the minimum inclination angle. That is, in thecompressor of Embodiment 1, the stroke of the movable body 13 a in thedirection of the driving axis O is shorter than that of the compressorin the comparative example.

Accordingly, the compressor of Embodiment 1 is capable of exhibitinghigh controllability and excellent mountability.

In particular, in this compressor, since the movable body 13 a directlyabuts on and presses the swash plate 5 via the acting portion 134 andthe protrusion 5 g, the direction of the load which acts on the swashplate 5 is less likely to vary. Consequently, in this compressor, themovable body 13 a easily presses the swash plate 5 in the direction ofthe driving axis O, and the movable body 13 a is able to stably changethe inclination angle of the swash plate 5. Furthermore, in thiscompressor, because the posture of the movable body 13 a is stable,leakage of the pressure from the control pressure chamber 13 b is lesslikely to occur.

Furthermore, in this compressor, in order to change the inclinationangle of the swash plate 5, the movable body 13 a merely abuts directlyon and presses the swash plate 5, and the acting portion 134 is notconnected to the protrusion 5 g with a connection pin or the like.Consequently, in this compressor, there is no risk that theconfiguration of a connecting portion changes the posture of the movablebody 13 a, and thus, the posture of the movable body 13 a is less likelyto change at the time of changing the inclination angle. Furthermore, inthis compressor, it is possible to suppress complication of theconfiguration and realize reduction in manufacturing cost.

Furthermore, in this compressor, the drive shaft 3 is inserted throughthe movable body 13 a, and the movable body 13 a is capable of beingfitted to the lug plate 51 by accommodating the movable body 13 a in thefixed cylindrical portion 51 a. Here, in this compressor, the thirdmovable cylindrical portion 133 of the movable body 13 a advances to theposition on the inner side of the thrust bearing 55 in the fixedcylindrical portion 51 a. Therefore, in this compressor, the space forallowing the movable body 13 a to move in the direction of the drivingaxis O can be suitably provided between the lug plate 51 and the swashplate 5 while making the axial length short. Furthermore, the thrustbearing 55 provided in the compressor can suitably receive the suctionreaction force and the compression reaction force which act on thepistons 9.

Furthermore, in this compressor, the control pressure chamber 13 b canbe suitably formed between the lug plate 51 and the movable body 13 a bythe fixed cylindrical portion 51 a. In this compressor, the hermeticityof the control pressure chamber 13 b is suitably ensured by the O-rings49 c and 49 d which are provided at the first and the third movablecylindrical portions 131 and 133 respectively.

Furthermore, in this compressor, the acting portion 134 and theprotrusion 5 g are located eccentrically toward the top-dead-centercorresponding portion T from the driving axis O, and the operativeposition F moves toward the driving axis O as described above as theinclination angle of the swash plate 5 decreases. Therefore, in thiscompressor, the space for allowing the movable body 13 a to move in thedirection of the driving axis O is easily provided between the lug plate51 and the swash plate without disrupting the change of the inclinationangle. Therefore, in this compressor, it is possible to increase thediameter of the actuator 13 to quickly move the movable body 13 a by asufficient thrust force. Also in this aspect, this compressor is capableof quickly changing the inclination angle in response to the drivingconditions of a vehicle.

Furthermore, in this compressor, the acting portion 134 protrudes fromthe first movable cylindrical portion 131 toward the top-dead-centercorresponding portion T of the swash plate 5 and is integrated with themovable body 13 a. Furthermore, the acting surface 134 a is formed atthe acting portion 134. Thereby, in this compressor, the acting surface134 a can easily abut on the protrusion 5 g at the position eccentrictoward the top-dead-center corresponding portion T from the driving axisO. Here, since the protrusion 5 g is formed to protrude in asubstantially hemispherical manner, the acting surface 134 a can besuitably brought into point-contact with the protrusion 5 g.Consequently, in this compressor, the contact area between the actingsurface 134 a and the protrusion 5 g can be made small, whereby theswash plate 5 can easily change its inclination angle.

Furthermore, the protrusion 5 g is integrally formed with the frontsurface 5 a of the swash plate main body 50. Therefore, in thiscompressor, it is possible to reduce the number of components,facilitate manufacturing, and reduce manufacturing cost.

Furthermore, in this compressor, the swash plate chamber 25 and thesuction chamber 33 communicate with each other through the suctionpassage 39. Thereby, in this compressor, the pressure in the swash platechamber 25 can be made low as well as the suction chamber 33.

Furthermore, the control mechanism 15 adjusts the pressure in thepressure regulation chamber 31 and thus the pressure in the controlpressure chamber 13 b by regulating the opening degree of the controlvalve 15 c. In addition, the axial path 3 a and the radial path 3 b areformed in the drive shaft 3. Consequently, in this compressor, it ispossible to suitably change the pressure in the control pressure chamber13 b and suitably move the movable body 13 a while downsizing thecontrol mechanism 15.

Furthermore, in this compressor, the hermeticity of the pressureregulation chamber 31 is suitably ensured by the O-rings 49 a and 49 bwhich are provided at the rear end of the drive shaft 3.

Embodiment 2

As shown in FIG. 10, in a compressor of Embodiment 2, the swash plate 5has the swash plate main body 50, the swash plate arms 5 e and 5 f and acontact member 59. The contact member 59 also corresponds to the actedportion in the present invention.

The contact member 59 is formed to be a separate body from the swashplate main body 50. The contact member 59 is attached to the frontsurface 5 a of the swash plate main body 50 at a position between theswash plate arms 5 e and 5 f, and located eccentrically toward thetop-dead-center corresponding portion T of the swash plate 5 from thedriving axis O.

A protrusion 59 a that protrudes frontward is formed at the contactmember 59. The protrusion 59 a is formed into a substantiallyhemispherical shape. The protrusion 59 a comes into point-contact withthe acting surface 134 a of the acting portion 134 at the operativeposition F. In this manner, in this compressor, via the acting surface134 a and the protrusion 59 a, the acting portion 134 abuts on thecontact member 59 at a position eccentric toward the top-dead-centercorresponding portion T of the swash plate 5 from the driving axis O.The other components of this compressor are the same as those of thecompressor of Embodiment 1, and, where the components are the same, samereference numerals are used and detailed explanation thereof is omitted.

In this compressor, since the swash plate 5 and the contact member 59are separate bodies, it is possible to improve the flexibility of designwith respect to the swash plate main body 50 and the contact member 59.The other operations of this compressor are the same as those of thecompressor of Embodiment 1.

Although the present invention has been described above in line withEmbodiments 1 and 2, it is needless to say that the present invention isnot limited to Embodiments 1 and 2 described above and may be modifiedand applied as appropriate without departing from the gist of theinvention.

For example, the compressors of Embodiments 1 and 2 may be configuredsuch that the operative position F moves toward the driving axis O whilethe inclination angle of the swash plate 5 decreases to a predeterminedangle from the maximum state, and the operative position F does not movewhile the inclination angle of the swash plate 5 reaches its minimuminclination angle from the predetermined angle.

Furthermore, the protrusion 5 g and the protrusion 59 a may be formedinto a flat-plate shape, and the acting surface 134 a of the actingportion 134 may be formed into a curved shape. This enables theprotrusion 5 g and the protrusion 59 a to come into line-contact withthe acting portion 134 at the operative position F.

Furthermore, the control mechanism 15 may be configured such that thecontrol valve 15 c is provided at the high pressure passage 15 b and theorifice 15 d is provided at the low pressure passage 15 a. In this case,the flow rate of the high-pressure refrigerant flowing through the highpressure passage 15 b can be regulated by the control valve 15 c.Therefore, due to the high pressure in the discharge chamber 35, thepressure in the control pressure chamber 13 b can be increased quicklyand the compression capacity can be decreased quickly. Furthermore,instead of the control valve 15 c, a three-way valve that is connectedto the low pressure passage 15 a and the high pressure passage 15 b maybe provided so that the flow rate of the refrigerant flowing through thelow pressure passage 15 a and the high pressure passage 15 b is adjustedby regulating an opening degree of the three-way valve.

INDUSTRIAL APPLICABILITY

The present invention is applicable to air-conditioning apparatus andthe like.

REFERENCE SIGNS LIST

-   -   1 HOUSING    -   3 DRIVE SHAFT    -   3 a AXIAL PATH (CONTROL PASSAGE)    -   3 b RADIAL PATH (CONTROL PASSAGE)    -   5 SWASH PLATE    -   5 d INSERTION HOLE    -   5 e, 5 f SWASH PLATE ARM (TRANSMISSION MEMBER)    -   5 g PROTRUSION (ACTED PORTION)    -   7 LINK MECHANISM    -   9 PISTON    -   11 a, 11 b SHOE (CONVERSION MECHANISM)    -   13 ACTUATOR    -   13 a MOVABLE BODY    -   13 b CONTROL PRESSURE CHAMBER (CONTROL PASSAGE)    -   15 CONTROL MECHANISM    -   15 a LOW PRESSURE PASSAGE (CONTROL PASSAGE)    -   15 b HIGH PRESSURE PASSAGE (CONTROL PASSAGE)    -   15 c CONTROL VALVE    -   25 SWASH PLATE CHAMBER    -   31 PRESSURE REGULATION CHAMBER    -   33 SUCTION CHAMBER    -   35 DISCHARGE CHAMBER    -   21 a CYLINDER BORE    -   49 a, 49 b O-RING (THIRD SEAL MEMBER)    -   49 c O-RING (FIRST SEAL MEMBER)    -   49 d O-RING (SECOND SEAL MEMBER)    -   51 LUG PLATE (LUG MEMBER)    -   51 a FIXED CYLINDRICAL PORTION    -   55 THRUST BEARING    -   59 CONTACT MEMBER (ACTED PORTION)    -   59 a PROTRUSION    -   131 FIRST MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL        PORTION)    -   132 SECOND MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL        PORTION)    -   133 THIRD MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL        PORTION)    -   134 ACTING PORTION    -   F OPERATIVE POSITION    -   O DRIVING AXIS    -   T TOP-DEAD-CENTER CORRESPONDING PORTION

1. A variable displacement swash plate type compressor comprising: ahousing in which a swash plate chamber and a cylinder bore are formed; adrive shaft that is rotatably supported by the housing; a swash platethat is rotatable in the swash plate chamber by rotation of the driveshaft; a link mechanism that is provided between the drive shaft and theswash plate and permits change of an inclination angle of the swashplate with respect to a direction perpendicular to a driving axis of thedrive shaft; a piston that is reciprocally accommodated in the cylinderbore; a conversion mechanism that reciprocates the piston in thecylinder bore at a stroke corresponding to the inclination angle byrotation of the swash plate; an actuator capable of changing theinclination angle; and a control mechanism that controls the actuator,wherein the link mechanism has a lug member that is fixed to the driveshaft in the swash plate chamber and a transmission member thattransmits rotation of the lug member to the swash plate, the actuatorhas the lug member, a movable body that is rotatable integrally with theswash plate and is capable of changing the inclination angle by movingin the direction of the driving axis, and a control pressure chamberthat is defined by the lug member and the movable body and moves themovable body by changing its internal pressure by the control mechanism,an acting portion that is capable of pressing the swash plate by thepressure in the control pressure chamber is formed at the movable body,an acted portion that abuts on and is pressed by the acting portion isformed at the swash plate, the acting portion abuts on the acted portionat an operative position, the operative position moves in accordancewith the change of the inclination angle, a top-dead-centercorresponding portion for positioning the piston at its top dead centeris defined in the swash plate, and the operative position when theinclination angle is maximum is closer to the top-dead-centercorresponding portion as compared to the operative position when theinclination angle is minimum.
 2. The variable displacement swash platetype compressor according to claim 1, wherein the drive shaft isinserted through the movable body, and the movable body is capable ofbeing fitted to the lug member.
 3. The variable displacement swash platetype compressor according to claim 2, wherein the movable body has amovable cylindrical portion that is formed into a cylindrical shape andcoaxial with the driving axis, and the lug member has a fixedcylindrical portion that is formed into a cylindrical shape and coaxialwith the driving axis at an outer circumferential side of the movablecylindrical portion to thereby provide the control pressure chamber inthe movable cylindrical portion.
 4. The variable displacement swashplate type compressor according to claim 3, wherein a first seal memberthat seals the control pressure chamber is provided between the movablecylindrical portion and the drive shaft, and a second seal member thatseals the control pressure chamber is provided between the movablecylindrical portion and the fixed cylindrical portion.
 5. The variabledisplacement swash plate type compressor according to claim 3, wherein athrust bearing that receives a thrust force which acts on the piston isprovided between the housing and the lug member, and the movablecylindrical portion is smaller in diameter than the thrust bearing andcapable of advancing to an inner side of the thrust bearing.
 6. Thevariable displacement swash plate type compressor according to claim 1,wherein the acting portion comes into point-contact or line-contact withthe acted portion at the operative position.
 7. The variabledisplacement swash plate type compressor according to claim 6, whereinthe acting portion and the acted portion are located eccentricallytoward the top-dead-center corresponding portion from the driving axis,and the operative position moves toward the driving axis as theinclination angle decreases.
 8. The variable displacement swash platetype compressor according to claim 7, wherein the acting portion has anacting surface that extends in the direction perpendicular to thedriving axis, and the acted portion has a protrusion that protrudes fromthe swash plate and abuts on the acting surface.
 9. The variabledisplacement swash plate type compressor according to claim 7, whereinthe movable body has a movable cylindrical portion that is formed into acylindrical shape and coaxial with the driving axis, and the actingportion protrudes from the movable cylindrical portion toward thetop-dead-center corresponding portion.
 10. The variable displacementswash plate type compressor according to claim 1, wherein the swashplate has a swash plate main body that is formed with an insertion hole,through which the drive shaft is inserted, and the acted portion that isintegrally formed with the swash plate main body.
 11. The variabledisplacement swash plate type compressor according to claim 1, whereinthe swash plate has a swash plate main body that is formed with aninsertion hole, through which the drive shaft is inserted, and the actedportion that is fixed to the swash plate main body.
 12. The variabledisplacement swash plate type compressor according to claim 1, wherein asuction chamber and a discharge chamber are formed in the housing, andthe suction chamber and the swash plate chamber communicate with eachother.
 13. The variable displacement swash plate type compressoraccording to claim 12, wherein the control mechanism has a controlpassage that provides communication between the control pressure chamberand the suction chamber and/or the discharge chamber and a control valvethat is capable of regulating an opening degree of the control passage,and at least a part of the control passage is formed in the drive shaft.14. The variable displacement swash plate type compressor according toclaim 13, wherein a pressure regulation chamber that communicates withthe control pressure chamber through the control passage and allows apressure therein to be changed by the control valve is formed betweenthe housing and one end of the drive shaft, and a third seal member thatseals the pressure regulation chamber is provided between the housingand the drive shaft.